Docker将变量传递到运行git clone的shell脚本中

Question

I am creating a Dockerfile and as part of this file, I am wanting to give the end user the option to pass in their git repo.

I looked at this SO post , and a few other sites but am stuck on the git clone syntax.

The git clone command returns an error as the variable that is part of it does not contain a value at the docker build stage.

I have this bash script called gitclone.sh

#!/bin/bash
git clone $1 /app

and in my Dockerfile I have this line:

RUN ./gitclone.sh $LOCATION

The shell script has the right permissions to run and it works when running it from within the container since I am passing an actual repository to it.

During the Docker build phase I get the following error:

fatal: repository '/app' does not exist

The directory is there, but the $1 is empty to the command doesn't work.

Question How do I make the Dockerfile work? The desired output I want it:

docker run -e LOCATION=https://github.com/something.git -d jwknz/pg02

UPDATE Changing my Dockerfile to contain CMD ["../gitclone.sh","$LOCATION"] instead of RUN ./gitclone.sh $LOCATION doesn't fix it.

The Dockerfile will build, but the container stops after running the docker run command.

Answer 1

First off, you have to notice that the Dockerfile is used to build your image (with the docker build command) and docker run is used to start a container from the already build docker image.

You have to define an entrypoint script. This is a script that is executed every time a container is started from the image you've build with the Dockerfile .

Assuming you want to clone a git repo and run apache httpd afterwards you can create a script like this in the same folder where your Dockerfile is. Name it, eg gitCloneAndRunHttpd.sh

#!/bin/bash 

git clone $LOCATION /app 
/usr/local/apache2/bin/apachectl -f /usr/local/apache2/conf/httpd.conf 

Then you have to modify your Dockerfile telling docker to copy the script file to your docker image, make it executable, en tell it to run it at container creation:

[...]

COPY ["gitCloneAndRunHttpd.sh", "/gitCloneAndRunHttpd.sh"]
RUN chmod +x /gitCloneAndRunHttpd.sh
ENTRYPOINT ["/gitCloneAndRunHttpd.sh"]

After this you build your docker image with the docker build command and then you can start creating containers from your image.

Every time you start a container from it with docker run -e LOCATION=https://github.com/some-git-repo.url -d your/image , the repo https://github.com/some-git-repo.url will be cloned from within the container to the /app folder and apache httpd will be started.

Note: If you are wondering what is going on in the SO post you mentioned, there the default entrypoint is used (/bin/sh), and /file.sh abc is the argument passed to that entrypoint , therefore the file.sh script is executed.